The present invention relates to a damped-action pyrotechnic actuator.
In particular, it relates to inclination actuators for ammunition suspended from a parachute, where the inclination is controlled by the action of an actuator on one of the shroud lines via a pulley for example. More generally, it relates to actuators where it is necessary to control or damp the displacement speed of the piston, and to maintain a high driving force right up to the limit of travel.
One of the disadvantages of pyrotechnic actuators is that the combustion of the pyrotechnic material causes a high initial pressure, as the piston starts its movement, which diminishes strongly as the piston reaches its limit of travel, the piston having acquired a high speed due in particular to the high initial pressure. As a result the piston strikes hard the stop at the limit of travel.
If, so as to avoid this impact, the pressure is reduced or the piston is braked there is a risk that the piston will not reach the stop position and will not be able to be locked in this position using the means provided for this purpose. This may be detrimental if, for example, the actuator must enable a device to attain a new stable position such that it continues to exert a compressive force on the actuator. This is the case for ammunition suspended from a parachute which must be inclined, if the inclination is controlled by the action of the actuator on one of the shroud lines under tension, for example.